JP2011220302A - Exhaust device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable favorable ignition even at a low temperature, in a constitution configured such that fuel is supplied to a catalyst converter and an ignition device from a common fuel adding valve which is arranged at an exhaust passage.SOLUTION: An exhaust device includes: the fuel adding valve 7 and a variable fuel pressure regulator are controlled, and first injection (track 7c) by first pressure and second injection (track 7d) which is performed after the first injection by second pressure P2 which is lower than the first pressure are performed. The track of the fuel and a degree of the dispersion of the fuel are varied, and by using the variation, the fuel can properly be supplied to both pre-treatment catalyst converter 8 and a glow plug 21 from the common fuel adding valve 7.

Description

  The present invention relates to an exhaust device capable of supplying fuel to an exhaust passage of an internal combustion engine.

  For the purpose of purifying exhaust gas, an exhaust device that supplies fuel to an exhaust passage of an internal combustion engine is widely used.

  In the apparatus disclosed in Patent Document 1, ignition means such as a glow plug is disposed at a position where fuel from a fuel addition valve provided in an exhaust passage directly contacts, and a catalyst is provided downstream of these fuel addition valve and glow plug. A converter is arranged. The fuel is ignited by the ignition means, and the catalytic converter is heated by the flame.

JP 2006-112401 A

  However, in the apparatus of Patent Document 1, since the ignition means such as a glow plug is arranged at a position where the fuel from the fuel addition valve directly contacts, ignition is not performed well at low temperatures such as during cold start. There is a fear.

  An object of the present invention is to enable good ignition even at low temperatures in a configuration in which fuel is supplied to a catalytic converter and an ignition device from a common fuel addition valve arranged in an exhaust passage.

The first aspect of the present invention is:
A catalytic converter disposed in the exhaust passage of the internal combustion engine;
A fuel addition valve that is disposed upstream of the catalytic converter and supplies fuel into the exhaust passage;
An ignition device capable of igniting the fuel supplied from the fuel addition valve;
A pressure adjusting device for adjusting the pressure of the fuel supplied to the fuel addition valve;
A controller for controlling the fuel addition valve and the pressure adjusting device,
At least one of the nozzle holes of the fuel addition valve is inclined toward the upstream side of the exhaust passage,
When the temperature of the catalytic converter is lower than a predetermined value, the controller controls the fuel addition valve and the pressure adjusting device to execute a plurality of injections that are performed successively and have different fuel pressures,
The plurality of injections includes a first injection by a first fuel pressure and a second injection by a second fuel pressure that is executed after the first injection and is smaller than the first fuel pressure. An exhaust system for an internal combustion engine including the exhaust gas.

  In this aspect, the fuel supplied from the common fuel addition valve into the exhaust passage can be supplied to the catalytic converter and the ignition device. The pressure adjusting device adjusts the pressure of the fuel supplied to the fuel addition valve. When the temperature of the catalytic converter is lower than a predetermined value, the controller controls the fuel addition valve and the pressure adjusting device to execute a plurality of injections that are performed successively and have different fuel pressures. The plurality of injections includes a first injection by a first fuel pressure and a second injection by a second fuel pressure that is executed after the first injection and is smaller than the first fuel pressure. Including. When the fuel pressure changes, the fuel trajectory and the degree of dispersion change. This can be used to appropriately supply fuel from the common fuel addition valve to the catalytic converter and the ignition device. Can also be ignited well. In addition, since at least one of the injection hole shafts of the fuel addition valve is inclined toward the upstream side of the exhaust passage, the fuel is injected in a direction opposite to the exhaust flow, so that the fuel addition valve is upstream of the addition valve. In addition to improving the dispersion of the injected fuel, the fuel trajectory by the first injection and the second injection can be greatly varied in the transverse direction of the exhaust passage, and the apparatus size in the exhaust flow direction is suppressed. It is also possible to do.

Another aspect of the present invention provides:
A catalytic converter disposed in the exhaust passage of the internal combustion engine;
A fuel addition valve that is disposed upstream of the catalytic converter and supplies fuel into the exhaust passage;
An ignition device capable of igniting the fuel supplied from the fuel addition valve;
A pressure adjusting device for adjusting the pressure of the fuel supplied to the fuel addition valve;
A controller for controlling the fuel addition valve and the pressure adjusting device,
At least one of the nozzle holes of the fuel addition valve is inclined toward the upstream side of the exhaust passage,
When the temperature of the catalytic converter is lower than a predetermined value, the controller controls the fuel addition valve and the pressure adjusting device to change the fuel pressure from the first fuel pressure to the first fuel pressure. An exhaust system for an internal combustion engine, wherein a single injection is performed while changing to a low second pressure. In this aspect, the same effect as the first aspect can be obtained.

  Preferably, the second fuel trajectory when the second fuel pressure is applied is more transverse to the exhaust passage than the first fuel trajectory when the first fuel pressure is used. Close to.

  In this aspect, fuel can be appropriately supplied from the common fuel addition valve to the catalytic converter and the ignition device in accordance with the interval from the fuel addition valve. Preferably, fuel passing through the first track is supplied to the catalytic converter, and fuel passing through the second track is supplied to the ignition member. Preferably, the apparatus further includes a first and / or a collision member for causing the supplied fuel to collide, and the fuel that has collided with the first collision member through the first track is supplied to the catalytic converter. The fuel that has collided with the second collision member through the second track is supplied to the ignition device.

  Preferably, the ignition means is disposed in the vicinity of the catalytic converter so as to be able to exchange heat with the catalytic converter. In this aspect, when the temperature of the catalytic converter is raised, the vicinity of the ignition means is raised by the thermal radiation, and the ignition of the fuel is promoted.

  Preferably, the controller controls the pressure adjusting device such that the fuel pressure increases as the exhaust speed increases. In this aspect, it is possible to supply fuel in an appropriate trajectory even when the exhaust speed changes.

  The means for solving the problems in the present invention can be used in combination as much as possible.

  According to the present invention, it is possible to satisfactorily ignite even at low temperatures.

It is a conceptual diagram of embodiment of this invention. It is a principal part enlarged view which shows a burner apparatus. It is sectional drawing which looked at the burner apparatus in the axial direction. It is sectional drawing which shows a variable fuel pressure regulator. It is a graph which shows the example of a setting of an air quantity / fuel pressure map. It is a flowchart which shows a fuel supply process. It is a graph which shows the change of fuel pressure.

  Preferred embodiments of the present invention will be described in detail below. However, it should be noted that the embodiments of the present invention are not limited to the following embodiments, and the present invention includes all modifications and applications included in the concept of the present invention defined by the claims. I must. The dimensions, materials, shapes, relative arrangements, and the like of the constituent elements described in the present embodiment are not intended to limit the technical scope of the invention only to those unless otherwise specified. .

  FIG. 1 shows a schematic configuration of an engine body 1 and its intake and exhaust system in the embodiment. The engine body 1 is an on-vehicle four-cycle diesel engine. An intake pipe 2 and an exhaust pipe 3 (exhaust passage) are connected to the engine body 1. An air flow meter 4 that outputs a signal corresponding to the flow rate of the intake air flowing through the intake pipe 2 is provided in the middle of the intake pipe 2. The air flow meter 4 measures the amount of intake air into the engine body 1.

The end of the exhaust pipe 3 is connected to a silencer (not shown) and is opened to the atmosphere at the outlet. In the middle of the exhaust pipe 3, the oxidation catalytic converter 6 and the NOx catalytic converter 26 are arranged in series in this order. The oxidation catalytic converter 6 reacts unburned components such as HC and CO with O ₂ to make CO, CO ₂ , H ₂ O and the like. As the catalyst material, for example, Pt / CeO ₂ , Mn / CeO ₂ , Fe / CeO ₂ , Ni / CeO ₂ , Cu / CeO ₂ or the like can be used. The NOx catalytic converter 26 preferably comprises an NOx storage reduction (NSR) converter. The NOx catalytic converter 26 occludes NOx in the exhaust when the oxygen concentration of the inflowing exhaust gas is high, and occludes when the oxygen concentration of the inflowing exhaust gas decreases and a reducing component (for example, fuel) exists. It has a function of reducing NOx. The NOx catalytic converter 26 may be a selective reduction type NOx catalytic converter (SCR: Selective Catalytic Reduction).

  A fuel addition valve 7, a pretreatment catalytic converter 8, and a glow plug 21 are disposed upstream of the oxidation catalytic converter 6 in the exhaust pipe 3. These fuel addition valve 7, pretreatment catalytic converter 8, and glow plug 21 constitute a burner device 30. The burner device 30 is disposed on the downstream side of the collective portion of the exhaust manifold connected to the engine. The fuel addition valve 7 can add liquid fuel (light oil) into the exhaust.

  The fuel tank 11 is connected to the fuel addition valve 7 via a fuel suction pipe 12, a low pressure fuel pump 13, a high pressure fuel pump 14, a fuel supply pipe 15 and a variable fuel pressure regulator 16. The fuel pumps 13, 14 suck the fuel stored in the fuel tank 11 through the fuel suction pipe 12 and discharge it to the fuel supply pipe 15, whereby the fuel is supplied to the fuel addition valve 7. A high pressure fuel pump 28 is provided in the pipe 27 to the cylinder fuel injection valve 9 installed in the engine body 1. The fuel pumps 13, 14, and 28 are, for example, mechanical, and operate using a driving force of an output shaft (crankshaft) (not shown) of the engine body 1. At least one of the fuel pumps 13, 14, and 28 may be an electric type.

  The variable fuel pressure regulator 16 adjusts the pressure of fuel discharged from the high-pressure fuel pump 14. As shown in FIG. 4, the variable fuel pressure regulator 16 includes a needle valve 17. The needle valve 17 includes a valve seat 17b having an orifice 17a that opens to a branch passage 18 branched from the fuel supply pipe 15, and a needle 17c that opens and closes the orifice 17a while being in contact with the valve seat 17b. Yes. The variable fuel pressure regulator 16 further includes a magnetic armature (not shown) that is integrally connected to the needle valve 17, a spring (not shown) that biases the armature downward (in the direction of closing the needle valve 17), and a magnetic armature (not shown). And a coil 19 for generating magnetic flux in a magnetic circuit composed of a core.

  Based on the required fuel pressure, the magnitude of the current to be supplied to the coil 19 is controlled, and when the magnetic flux in the magnetic circuit composed of the magnetic core and the armature is changed, the force for biasing the armature downward is controlled. Thus, the biasing force of the spring is assisted, and the opening degree of the needle valve 17 is adjusted.

  When the coil 19 is not energized, the needle valve 17 is most open, and in the vicinity thereof, the fuel pressure becomes the second pressure P2 (for example, 5 MPa). When the current supplied to the coil 19 is gradually increased, the needle valve 17 is gradually closed and the fuel pressure is increased. When the supply current is in the vicinity of the maximum value, the discharged fuel is controlled to the first pressure P1 (for example, 10 MPa). The fuel pressure regulator may be of another configuration, for example, a type in which the spring pressure of the spring is set to a value corresponding to the maximum fuel pressure, and the fuel pressure is adjusted by urging the armature upward by the coil 19 and compressing it. Good.

  A pretreatment catalytic converter 8 for reforming the fuel injected from the fuel addition valve 7 is provided in a portion of the exhaust pipe 3 between the fuel addition valve 7 and the oxidation catalytic converter 6. The pretreatment catalytic converter 8 can be configured as an oxidation catalytic converter in which rhodium or the like is supported on a zeolite carrier, for example.

  When the fuel is supplied to the pretreatment catalytic converter 8, if the pretreatment catalytic converter 8 is activated at that time, the fuel is oxidized in the pretreatment catalytic converter 8. The temperature of the processing catalytic converter 8 is raised. Further, when the temperature of the pretreatment catalytic converter 8 is increased, hydrocarbons having a large number of carbon atoms in the fuel are decomposed to generate hydrocarbons having a small number of carbon atoms and high reactivity, whereby the fuel is a highly reactive fuel. To be modified. In other words, the pretreatment catalytic converter 8 constitutes a rapid heat generator that rapidly generates heat on the one hand, and a reformed fuel discharger that discharges the reformed fuel on the other hand. Further, part or all of the fuel supplied from the fuel addition valve 7 is heated or ignited by the glow plug 21, thereby promoting the temperature increase of the exhaust gas.

  In FIG. 2, the fuel addition valve 7 has a single injection hole 7 a, and the injection hole shaft 7 b of the injection hole 7 a includes a component in a direction crossing the exhaust pipe 3 and is upstream of the exhaust pipe 3. Inclined towards. The outer diameter of the pretreatment catalytic converter 8 is smaller than the inner diameter of the exhaust pipe 3, and when the pretreatment catalytic converter 8 is accommodated in the exhaust pipe 3, the outer peripheral surface of the pretreatment catalytic converter 8 and the inner peripheral surface of the exhaust pipe 3. Exhaust gas can pass through the catalyst bypass route, which is a gap between The pretreatment catalytic converter 8 is a so-called straight flow type in which individual cells communicate from upstream to downstream. The pretreatment catalytic converter 8 is disposed in a substantially cylindrical outer frame 8a, and the outer frame 8a is supported in the exhaust pipe 3 by a plurality of stays 8b disposed in a generally radial manner. The pretreatment catalytic converter 8 is surrounded by a catalyst detour around substantially the entire circumference except for the stay 8b.

  As shown in FIGS. 2 and 3, the exhaust pipe 3 is formed in a substantially cylindrical shape. Since the axis of the exhaust flow direction in the pretreatment catalytic converter 8 is deflected downward in the figure relative to the axis of the exhaust pipe 3 in the exhaust flow direction, the above-described catalyst bypass circuit has a wide side on the upper side in the figure. The detour 3b is a narrow side detour 3c having a narrow lower side.

  The glow plug 21 is disposed downstream of the fuel addition valve 7 and upstream of the pretreatment catalytic converter 8. The glow plug 21 is connected to the in-vehicle DC power source 23 via the booster circuit 22 and can ignite the fuel supplied from the fuel addition valve 7 by heat generated when energized. The glow plug 21 has an axis that is inclined toward the upstream side of the exhaust pipe 3. For example, the glow plug 21 may be arranged in any direction that is orthogonal to the flow direction and parallel to the longitudinal direction of the first collision plate 20 a described below. Can be placed in a posture. In addition, as an ignition means, other apparatuses, such as a ceramic heater and a spark plug, especially an electrothermal type or a spark ignition type apparatus can be used.

  A lower portion of the front end portion of the outer frame 8a that houses the pretreatment catalytic converter 8 is a bowl-shaped protruding portion 8b that protrudes toward the upstream side. A substantially flat first collision plate 20a is fixed to the protruding portion 8b. The first collision plate 20a is disposed at a position deflected downward in the exhaust pipe 3, and is slightly inclined toward the downstream side.

  A substantially flat second collision plate 20 b is disposed on the axis of the heat generating portion 21 a at the tip of the glow plug 21. The second collision plate 20b is disposed at a position deflected upward in the exhaust pipe 3, and is slightly inclined toward the upstream side.

  The 1st collision board 20a and the 2nd collision board 20b can be formed from the material excellent in heat resistance and impact resistance, such as SUS. The fuel addition valve 7 injects the fuel obliquely downward toward the collision plates 20a and 20b. The trajectory of the fuel supplied from the fuel addition valve 7 includes a component in a direction crossing the exhaust pipe 3. The collision plates 20a and 20b promote atomization and atomization of the fuel when the fuel collides, and improve dispersibility and diffusibility. The fuel that has collided with the collision plates 20a and 20b is deflected downstream by the exhaust flow. The fuel that has collided with the first collision plate 20a is mainly supplied to the pretreatment catalytic converter 8. The fuel that has collided with the second collision plate 20 b is mainly supplied to the heat generating portion 21 a of the glow plug 21.

  As shown in FIGS. 2 and 3, the transverse direction of the exhaust pipe 3 between the collision point 20 b 1 of the second collision plate 20 b where the fuel supplied from the fuel addition valve 7 collides and the injection hole 7 a of the fuel addition valve 7. The distance d2 is smaller than the distance d1 in the transverse direction of the exhaust pipe 3 between the collision point 20a1 of the first collision plate 20a where the fuel supplied from the fuel addition valve 7 collides and the injection hole 7a of the fuel addition valve 7. In other words, the collision point 20b1 of the second collision plate 20b and the collision point 20a1 of the first collision plate 20a are arranged at different positions in the width direction (that is, the transverse direction) of the exhaust pipe 3. The fuel injected from the nozzle hole 7a collides with the collision point 20a1 of the first collision plate 20a through the track 7c when the fuel pressure is changed to the first pressure P1 by the variable fuel pressure regulator 16 described above, and the fuel pressure is set to the second pressure. When the pressure P2 is reduced, the collision occurs through the track 7d and the collision point 20b1 of the second collision plate 20b. In the transverse direction of the exhaust pipe 3, the track 7d is closer to the nozzle hole 7a than the track 7c.

  The fuel that has moved (flyed) beyond the front end of the second collision plate 20b is mainly supplied to the pretreatment catalytic converter 8, and the fuel that has not exceeded the front end of the second collision plate 20b is supplied mainly to the glow plug 21. The That is, the second collision plate 20b in the present embodiment is a collision body that promotes atomization and atomization of the fuel and improves dispersibility and diffusibility when the fuel collides with the pretreatment catalytic converter 8. It can be said that it is a separator for separating fuel from the glow plug 21. At least one of the first collision plate 20a and the second collision plate 20b can be omitted.

  The glow plug 21 is disposed in the vicinity of the pretreatment catalytic converter 8, thereby enabling heat exchange with the pretreatment catalytic converter 8. That is, the glow plug 21 is positioned such that when the temperature of the pretreatment catalytic converter 8 is increased, the temperature of the vicinity of the heat generating portion 21a is increased by the thermal radiation, and the ignition of the fuel supplied from the fuel addition valve 7 is promoted. Is arranged. For this purpose, a gap 31 is provided between the downstream end of the second collision plate 20b and the pretreatment catalytic converter 8, and the radiant heat from the pretreatment catalytic converter 8 is blocked by the second collision plate 20b. It is made to act on the vicinity including the heat generating part 21a of the glow plug 21 without being damaged.

  The engine body 1 is provided with an ECU 10 that is an electronic control unit for controlling the driving state in accordance with the operating conditions of the engine body 1 and the driver's request. The ECU 10 includes a CPU that executes various arithmetic processes related to the control of the engine body 1, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores arithmetic results of the CPU, and the like. An input / output port for inputting / outputting signals is provided.

  In addition to the air flow meter 4, the ECU 10 includes a crank position sensor 24 that detects the crank angle of the engine body 1, an accelerator opening sensor 25 that outputs an electric signal corresponding to the accelerator opening, and exhaust gas downstream of the NOx catalytic converter 26. A NOx sensor 32 arranged in the passage, a water temperature sensor 33 for detecting the engine cooling water temperature, a SOx sensor 34 made of a solid electrolyte provided in the vicinity of the inlet of the NOx catalytic converter 26, and a vehicle speed arranged in the vicinity of a driving wheel (not shown). Various sensors including a vehicle speed sensor 35 for detecting the above are connected via electric wiring, and these output signals are input to the ECU 10. Further, the ECU 10 is connected to the fuel addition valve 7, the in-cylinder fuel injection valve 9, and the like via electric wiring, and these on-off valves are controlled by the ECU 10. The ECU 10 can detect the engine speed based on the output value of the crank position sensor 24 and can detect the required load of the engine body 1 based on the output value of the accelerator opening sensor 25.

  In the present embodiment, the ECU 10 performs the temperature raising process by the ignition of fuel, the PM oxidation process for the pretreatment catalytic converter 8 and the oxidation catalytic converter 6, the NOx reduction process for the NOx catalytic converter 26, and the SOx poisoning recovery process. The fuel addition valve 7 is controlled to inject fuel into the exhaust, and this fuel is supplied to the pretreatment catalytic converter 8, the oxidation catalytic converter 6, and the NOx catalytic converter 26. A part of the supplied fuel is ignited by the glow plug 21, and the other mainly liquid phase part is supplied to the pretreatment catalytic converter 8.

  The injection amount of fuel injected into the fuel addition valve 7 can be set for each control such as the NOx reduction process, the SOx poisoning recovery process, and the PM regeneration process described above. In the ROM of the ECU 10, a target total injection amount calculation map for calculating a target total injection amount that matches the operating state of the engine body 1 includes the above-described processing types (temperature increase process by ignition of fuel, oxidation process, NOx). (Reduction process, SOx poisoning recovery process, PM regeneration process, etc.). When performing the fuel injection control, the ECU 10 detects the engine speed, the accelerator opening, and the intake air amount, and uses these as parameters to access the target total injection amount calculation map to calculate the target total injection amount. The ECU 10 calculates the valve opening time so that the target total injection amount of fuel is injected from the fuel addition valve 7. Then, the ECU 10 issues a command to the fuel addition valve 7 (specifically, a drive mechanism (not shown) that drives the fuel addition valve 7 to open and close) to open the fuel addition valve 7 and the calculated valve opening time. The valve is closed when has elapsed. The above is the normal fuel supply control.

  The ROM of the ECU 10 further stores an air amount / fuel pressure map in which the intake air amount and the target pressures P1, P2 of the variable fuel pressure regulator 16 are stored in association with each other. In this air amount / fuel pressure map, as shown in FIG. 5, the larger the intake air amount, the higher the first pressure P1 and the second pressure P2, which are target pressures, are set. Instead of the intake air amount, another parameter having a correlation with the exhaust speed may be used.

  In the present embodiment configured as described above, the ECU 10 controls the fuel addition valve 7 and the variable fuel pressure regulator 16 so that when the temperature of the pretreatment catalytic converter 8 is lower than a predetermined value, the ECU 10 performs the fuel continuously. A plurality of injections with different pressures are executed.

  In FIG. 6, first, the ECU 10 reads the values of the parameters related to the state of the pretreatment catalytic converter 8 and the driving state of the vehicle (S10). The parameters read here are the engine speed detected by the crank position sensor 24, the required load detected by the accelerator opening sensor 25, the fuel injection amount from the in-cylinder fuel injection valve 9 set separately by the ECU 10, The coolant temperature detected by the water temperature sensor 32, the NOx amount downstream of the catalyst detected by the NOx sensor 32, and the SOx concentration detected by the SOx sensor 34 are included.

Next, the ECU 10 determines whether a predetermined fuel supply condition is satisfied (S20). The fuel supply condition is, for example, that both a catalyst request based on the state of the catalytic converters 8, 6, and 26 and a processing execution request based on the driving state of the vehicle are satisfied. The catalyst requirements are, for example, “the estimated temperature of at least one of the catalytic converters 6 and 26 is lower than a predetermined value”, “the NOx occlusion amount of the NOx catalytic converter 26 is larger than a predetermined value”, “NOx purification of the NOx catalytic converter 26” This is established when either of them is satisfied, that is, “the amount is greater than a predetermined value” and “the SOx (sulfur oxide) deposition amount of the NOx catalytic converter 26 is greater than a reference value”.
The estimated temperature of the catalytic converters 6 and 26 can be calculated by a predetermined function or map based on, for example, the exhaust gas temperature, the cooling water temperature, and the intake air temperature. The NOx occlusion amount of the NOx catalytic converter 26 is, for example, a predetermined function or map as an integrated value from the execution of the previous reduction process of the NOx amount discharged from the in-cylinder fuel injection valve 9 and the engine speed. Can be calculated. The NOx purification amount of the NOx catalytic converter 26 is a value indicating the NOx purification capacity of the catalyst material, and is obtained, for example, by subtracting the NOx amount downstream of the catalyst from the estimated NOx emission amount from the engine body 1. The estimated NOx emission amount is estimated based on the engine operating state, that is, the engine rotation speed and the fuel injection amount from the in-cylinder fuel injection valve 9 (the accelerator opening or the throttle opening may be used instead). The NOx amount downstream of the catalyst is detected by the NOx sensor 32. The SOx accumulation amount of the NOx catalytic converter 26 is calculated as, for example, an integrated value after the previous processing of the sulfur concentration in the fuel and the fuel consumption amount in the engine body 1. The detected value of the SOx sensor 34 can be used as the sulfur concentration in the fuel, but a fixed value or a known value provided from a gas station or a fuel dealer may be used. When the NOx catalytic converter 26 is a urea selective reduction type NOx catalyst, “the ammonia storage amount of the NOx catalytic converter 26 is less than a predetermined value” may be one of the catalyst requirements. The processing execution request is, for example, “the vehicle speed is being decelerated”. If the fuel supply condition is not satisfied, the processing after step S30 is skipped, and the processing is returned.

  If the determination in step S20 is affirmative, that is, if the fuel supply condition is satisfied, the ECU 10 next determines whether the warm-up of the pretreatment catalytic converter 8 has been completed (S30). This determination is made by comparing the estimated temperature of the pretreatment catalytic converter 8 with a predetermined value, and is affirmed when the estimated temperature exceeds the predetermined value. The estimated temperature of the pretreatment catalytic converter 8 can be obtained by a predetermined function or map based on the engine water temperature detected by the water temperature sensor 33, for example, but is detected by installing a dedicated temperature sensor in the pretreatment catalytic converter 8. May be.

  If the determination in step S30 is affirmative, the ECU 10 executes the normal fuel supply control described above (S80). As a result, the target process is executed among the temperature raising process by the ignition of fuel, the PM oxidation process for the pretreatment catalytic converter 8 and the oxidation catalytic converter 6, the NOx reduction process for the NOx catalytic converter 26, and the SOx poisoning recovery process. .

  If NO in step S30, that is, if the warm-up of the pretreatment catalytic converter 8 has not ended yet, the ECU 10 refers to the above-described air amount / fuel pressure map, and thereby the first pressure P1 and the second pressure that are target pressures. The pressure P2 is calculated (S40).

  Then, the ECU 10 injects fuel with the first pressure P1 (S50, solid line a in FIG. 7, from t1 to t2), and subsequently injects fuel with the second pressure P2 (S70, from t3 to t4). . The injection pressure is changed by controlling the variable fuel pressure regulator 16. When changing the fuel pressure, the injection by the fuel addition valve 7 is once closed, and a pause time (S60, from t2 to t3) is provided between the injection by the first pressure P1 and the injection by the second pressure P2. This pause period is preferably set to a length that allows the pretreatment catalytic converter 8 to generate heat well by the first injection at the first pressure P1 and support subsequent ignition by the glow plug 21. However, without providing such a downtime, as indicated by a one-dot chain line b in FIG. 7, the injection may be performed stepwise from the injection by the first pressure P1 to the injection by the second pressure P2. The process exits this routine on the condition that the second injection has ended.

  The fuel injected by the first pressure P1 from the fuel addition valve 7 collides with the first collision plate 20a through the track 7c, and the reflected or attached fuel is supplied to the pretreatment catalytic converter 8 by the exhaust flow. The first collision plate 20a promotes atomization and atomization of the fuel when the fuel collides, and improves dispersibility and diffusibility. By supplying the fuel, the temperature of the pretreatment catalytic converter 8 is raised, and the supplied fuel is reformed to a highly reactive fuel. By supplying the reformed fuel to the oxidation catalyst converter 6 and / or the NOx catalyst converter 26, PM regeneration processing, NOx reduction processing, SOx poisoning recovery processing, and the like can be performed smoothly.

  The fuel injected by the second pressure P2 collides with the second collision plate 20b through the track 7c, or is directly supplied to the vicinity of the heat generating portion 21a of the glow plug 21 and ignited. Since the pretreatment catalytic converter 8 is heated by the previous injection of the first pressure P1, the vicinity of the heat generating portion 21a is heated by the heat radiation, and the ignition of the fuel is promoted.

  As described above, in the present embodiment, the ECU 10 controls the fuel addition valve 7 and the variable fuel pressure regulator 16 to execute a plurality of injections that are performed successively and have different fuel pressures. If the fuel is always supplied at the first pressure P <b> 1, the fuel is not distributed in the vicinity of the glow plug 21 and may not be suitable for ignition in the glow plug 21. On the other hand, if the collision member is disposed in the vicinity of the tip of the fuel addition valve 7, it is suitable for ignition by the glow plug 21, but the supply of fuel to the pretreatment catalytic converter 8 becomes insufficient. On the other hand, in the present embodiment, since a plurality of injections that are performed successively and have different fuel pressures are executed, the fuel trajectory and the degree of dispersion change, and this is used to make a common fuel addition valve. 7, fuel can be appropriately supplied to both the pretreatment catalytic converter 8 and the glow plug 21.

  Further, the glow plug 21 is disposed in the vicinity of the pretreatment catalytic converter 8, and a plurality of injections are performed after the first injection by the first pressure P1 and the first injection, which is performed after the first injection and is smaller than the first pressure. 2nd injection by 2 pressure P2. As a result, when the fuel supplied by the first injection is supplied to the pretreatment catalytic converter 8, the temperature in the vicinity thereof increases due to the heat generated by the pretreatment catalytic converter 8, so that the second injection is performed thereafter. Thus, when fuel is supplied to the glow plug 7, ignition can be promoted and misfire can be suppressed.

  Further, the fuel tracks 7 c and 7 d supplied from the fuel addition valve 7 include components in a direction crossing the exhaust pipe 3, and the exhaust pipe 3 between the collision point 20 b 1 of the second collision plate 20 b and the fuel addition valve 7 is included. The transverse distance d2 is smaller than the transverse distance d1 of the exhaust pipe 3 between the collision point 20a1 of the first collision plate 20a and the fuel addition valve 7. As a result, fuel can be appropriately supplied from the common fuel addition valve 7 to the pretreatment catalytic converter 8 and the glow plug 21 according to the distance in the transverse direction of the exhaust pipe 3 from the fuel addition valve 7. Become.

  In the present embodiment, the nozzle hole shaft 7b of the fuel addition valve 7 is inclined toward the upstream side of the exhaust passage. Therefore, by injecting fuel in a direction that opposes the exhaust flow, In the upstream region, the dispersion of the injected fuel can be improved, and the fuel trajectory by the first injection and the second injection can be greatly varied in the transverse direction of the exhaust passage, and the exhaust flow direction It is also possible to suppress the size of the apparatus.

  In the present embodiment, the ECU 10 controls the variable fuel pressure regulator 16 so that the fuel pressures P1 and P2 increase as the exhaust speed increases. Therefore, even when the exhaust speed changes, the ECU 10 supplies fuel on the appropriate tracks 7c and 7d. It becomes possible to supply.

  Although the invention has been described with a certain degree of particularity, it should be understood that various modifications and changes can be made without departing from the spirit and scope of the claimed invention. Embodiments of the present invention are not limited to the above-described embodiments, and the present invention includes all modifications and applications included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention. The means for solving the problems in the present invention can be used in combination as much as possible.

  For example, when the fuel addition valve 7 has a plurality of injection holes, it is sufficient that there is at least one injection hole whose injection hole axis is inclined toward the upstream side of the exhaust passage. The effect of can be obtained.

  Further, as indicated by a two-dot chain line c in FIG. 7, the ECU 10 may cause the fuel addition valve 7 to execute a single injection while continuously changing the fuel pressure. The ECU 10 can control the variable fuel pressure regulator 16 and the fuel addition valve 7 to execute injection with patterns other than those described above. For example, the injection performed while continuously changing the fuel pressure may be performed a plurality of times, or the injection performed while continuously changing the fuel pressure and the injection performed while keeping the fuel pressure constant may be performed continuously. Three or more injections may be performed continuously, and the injection by the first pressure, the injection by the second pressure P2, and the injection performed while changing the fuel pressure can be combined in any order, and the pause time between them Whether or not to provide is also arbitrary. How to set the ratio between the first injection and the second fraction is also arbitrary. For example, the ratio and the length of the first injection may be set larger as the temperature of the pretreatment catalytic converter 8 is lower.

  Moreover, the arrangement method and shape of the collision plate can be appropriately changed within the range having the function of atomizing the fuel injected from the fuel addition valve 7 and the function of guiding the fuel to the pretreatment catalytic converter 8. . Each collision plate may be provided with an arbitrary number of through holes, concave portions and / or convex portions. The longitudinal section of the collision plate may be arcuate instead of straight. A configuration without a collision plate can also be employed. In this case, the fuel from the fuel addition valve 7 may collide with the tube wall of the exhaust pipe 3.

  At least one of the pretreatment catalytic converter and the exhaust pipe may have a non-circular cross section such as an ellipse or an oval cross section. The interval in the transverse direction of the exhaust pipe 3 may be such that the pretreatment catalytic converter 8 is closer to the fuel addition valve 7 than the heat generating portion of the glow plug 21 (ignition device).

  The cross section of the pretreatment catalytic converter 8 in the transverse direction of the exhaust pipe 3 may extend over the entire interior of the exhaust pipe 3. The type and order of other exhaust treatment apparatuses existing downstream of the pretreatment catalytic converter 8 are also arbitrary.

1 Engine Body 3 Exhaust Pipe 6 Oxidation Catalytic Converter 7 Fuel Addition Valve 8 Pretreatment Catalytic Converter 9 In-Cylinder Fuel Injection Valve 10 ECU
16 Variable fuel pressure regulator 20a First collision plate 20b Second collision plate 21 Glow plug 21a Heating part 26 NOx catalytic converter 30 Burner device

Claims (5)

A catalytic converter disposed in the exhaust passage of the internal combustion engine;
A fuel addition valve that is disposed upstream of the catalytic converter and supplies fuel into the exhaust passage;
An ignition device capable of igniting the fuel supplied from the fuel addition valve;
A pressure adjusting device for adjusting the pressure of the fuel supplied to the fuel addition valve;
A controller for controlling the fuel addition valve and the pressure adjusting device,
At least one of the nozzle holes of the fuel addition valve is inclined toward the upstream side of the exhaust passage,
When the temperature of the catalytic converter is lower than a predetermined value, the controller controls the fuel addition valve and the pressure adjusting device to execute a plurality of injections that are performed successively and have different fuel pressures,
The plurality of injections includes a first injection by a first fuel pressure and a second injection by a second fuel pressure that is executed after the first injection and is smaller than the first fuel pressure. An exhaust system for an internal combustion engine comprising: A catalytic converter disposed in the exhaust passage of the internal combustion engine;
A fuel addition valve that is disposed upstream of the catalytic converter and supplies fuel into the exhaust passage;
An ignition device capable of igniting the fuel supplied from the fuel addition valve;
A pressure adjusting device for adjusting the pressure of the fuel supplied to the fuel addition valve;
A controller for controlling the fuel addition valve and the pressure adjusting device,
At least one of the nozzle holes of the fuel addition valve is inclined toward the upstream side of the exhaust passage,
When the temperature of the catalytic converter is lower than a predetermined value, the controller controls the fuel addition valve and the pressure adjusting device to change the fuel pressure from the first fuel pressure to the first fuel pressure. An exhaust system for an internal combustion engine, wherein a single injection is performed while changing to a low second pressure. An exhaust system for an internal combustion engine according to claim 1 or 2,
The second trajectory of the fuel at the time of the second fuel pressure is closer to the fuel addition valve in the transverse direction of the exhaust passage than the first trajectory of the fuel at the time of the first fuel pressure. An exhaust system for an internal combustion engine characterized by the above. An exhaust system for an internal combustion engine according to any one of claims 1 to 3,
The exhaust system for an internal combustion engine, wherein the ignition means is disposed in the vicinity of the catalytic converter so as to be able to exchange heat with the catalytic converter. An exhaust system for an internal combustion engine according to any one of claims 1 to 4,
An exhaust system for an internal combustion engine, wherein the controller controls the pressure regulator so that the fuel pressure increases as the exhaust speed increases.

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